Although various cutaneous manifestations can occur in patients with chronic lymphocytic leukemia (CLL), bullous lesions due to mosquito bites are rare. We describe a patient with a typical case of CLL complicated by exaggerated cutaneous response to mosquito bites. The symptoms of this patient were self-limited and not severe, but it has been reported that the treatment of such symptoms is sometimes difficult. Because exaggerated cutaneous hypersensitivity to mosquito bites can be observed even before the diagnosis of hematological malignancies such as CLL, careful examinations are recommended to find underlying diseases in cases in which this type of cutaneous reaction occurs.